The subject system and method are generally directed to enhancing a data signal that is generated within an integrated circuit chip for chip-to-chip transmission between source and destination (or driver and receiver) circuits without incurring excessive loss or degradation. More specifically, the subject system and method are directed to boosting a selective portion of a drive signal accordingly generated at a driver for the data signal, so that it may be transmitted through various intervening structures/media and on to the receiver with its integrity substantially preserved.
With ongoing advances in integrated circuit (IC) fabrication technology, and the ongoing development of high speed computer, network, and other telecommunication systems, electronic designs operating at higher frequencies are becoming more prevalent. Collective/effective data rates on the order of 10 gigabits (Gbits), for instance, are not uncommon. In these types of applications, the attenuation due to physical interconnections, impedance mismatches, skin effect, and the like at the chip, package, board, connector, cable, and/or test channel/backplane levels are not negligible. At high operational frequencies, an interconnection for example may be greater in its physical length than a transmitted signal's effective electrical length. Also, there tends to be heightened sensitivity to transients and other factors which might otherwise be negligible.
For reliable transmission of a drive signal generated on chip at one side of an interconnection interface to a receiver chip at the other side of the interconnection interface, the drive signal must have ample margin to withstand the various intervening sources of attenuation. Complicating the matter is the fact that certain spectral components of a signal may encounter greater attenuation than other spectral components. In certain applications, for example, higher frequency components of a drive signal may be attenuated more than the lower frequency components.
Of course, one might simply raise the supply voltage for a given application to high enough level to try and ensure sufficient peak voltage margin in the drive signal. This is the very approach oft taken in the art, but the resultant increase in current consumption and power is a prohibitive factor in many applications. Unduly heightened supply voltages tend to also strain other requirements, particularly as applications increasingly employ shorter channel length technologies.
Simply raising the supply voltages also fails to adequately address problems such as inter symbol interference (ISI), a type of data dependent jitter (noise) caused by unequal attenuation effects on different frequency contents of data. Ideally, signal integrity would be preserved at the far end of a given transmission. ISI during transmission distorts that far end signal, largely nullifying what near end benefits might result from this approach of simply raising supply voltage levels.
Other approaches generally known in the art for preserving drive signal integrity include emphasis, whereby equalization-type techniques are applied to improve the overall signal to interference ratio of the drive signal. For example, de-emphasis measures are employed to decrease the magnitudes of certain lower frequencies toward that end; however, this residual attenuation of lower frequency constituents limits the usefulness of this approach for reliably preserving the eye opening of a drive signal.
There is therefore a need for a system or method whereby a drive signal may be suitably presented at near and far ends of transmission across an interconnection interface without loss of integrity, while overcoming these and other drawbacks. There is a need for such system or method which maintains the eye opening of a drive signal sufficiently at both the near and far ends of an attachment unit interface.